It is well known by billiard players that the curvature or convexity of the tip of the cue stick is a matter of considerable importance. Every time the cue strikes a ball, the shape of the tip is slightly altered, and long use will flatten the tip centrally, causing the edges to project beyond the body of the cue. The best players of the game are the most carefull to secure a uniform curvature for the tip of the cue stick and they attempt to preserve that curvature.